My Favourite Fraud

August 18, 2010

By: Marc Obrowski

The trickiest (and funniest) toll collector fraud I have ever seen can not happen in India. Sometimes I wish it could. You could make a film of it. If Bollywood were in the Philippines I am sure this would already have happened. Only problem: this story has a really bad ending. Let me explain.

My favourite toll audit tool is statistical analysis. The idea is simple: Fraud is an irregularity. If you look at the right data in the right way this irregularity will somehow show in your graphs and tables. I like it because it’s geek work. It’s only you and data. No people skills needed.

My alarm bells ring when I look at some data of the North Luzon Expressway in the Philippines:

Analysis number 1: Number of exempt (i.e. free) transactions per toll collector. Employee number 54312 had more than 10 times the average. And more than twice as the next collector in the ranking. Can’t be. Let’s fire 54312. Wait… let’s do some more checks first.

Analysis number 2: Number of exempt transactions by toll plaza and by toll lane. Lane 2 of plaza X has more than any other lane. Can’t be. Let’s fire lane 2. Wait a minute…

Analysis number 3: Who worked in plaza X? It was mainly 54312 and four others. They all had more exempt transactions than collectors in other plazas. But when 54312 was on duty (always in lane 2) it was rampant. Almost all exempts where recorded in that lane, almost none in the other 3. There are thus three factors: the plaza, the lane and the collector.

Now I hate it. Sifting through data alone won’t do it. I actually have to go out and talk to people. Geek time over.

I ended up talking to many. And here are the results.

Plaza X is where the patrol vehicle depot is. The lion share of exempts is with those cars. But why are suddenly all our patrol cars recorded only at lane 2 when 54312 is on duty? If I weren’t such a geek it would have dawned on me the moment I met collector 54312.

54312 goes by the name of Juanita de la Cruz (name changed for her protection from readers like you). And she is devastatingly pretty. The patrollers knew that her lane was number 2. Do I need to explain more? There was no fraud after all.

Oh, yes, the bad ending. Here it comes: Juanita married Francisco, a handsome patroller.

This is a true story. It happened in 2004.